Keep an eye on the trunks. The pics are too small on my monitor to see. If you get rusty spots with one little hole in the center you need to worry about the Bronze Borers. That's what takes out most of our White Birches down the road in MD. Haven't tried the product you posted. I believe we used to use Cygon or Dursban for treatment. Both are restricted chemicals so you would need to contact a licensed tree expert to treat it. But, I can't see any sign of BBB in the pics, Joe.